Background Effective decision making in health care relies upon evidence-based measures of relative disease frequency, mortality and morbidity. Findings from the first Global Burden of Disease (GBD) study showed for the first time the high level of health loss, or ‘burden’, associated with mental disorders relative to other high priority public health issues. A major contribution to the mental health burden comes from anxiety disorders yet there has been no comprehensive assessment of the global frequency or extent of health loss from this group of common mental disorders. Accurate estimates for the prevalence and burden of anxiety disorders, relative to other health issues, across populations and over time, are needed to inform policy decisions around resource re-allocation, service provision and research priorities. The new Global Burden of Disease Study (GBD 2010) aimed to produce estimates of fatal and non-fatal disease burden using improved data and modelling techniques for a more complete range of disease and injury categories. This new initiative provided an opportunity to produce, for the first time, estimates for the global prevalence and burden of anxiety disorders. This thesis addresses the data input and methods required to synthesise populationrepresentative measures of health loss to inform health policy, and the application of these in calculating the prevalence and burden of anxiety disorders. Methods A series of systematic reviews were conducted for epidemiological studies reporting prevalence, incidence, remission and excess mortality for all mental disorders captured in GBD 2010. I collated and assessed information on data availability and study quality, identifying strengths and weaknesses in the current research and calculated regional coverage for prevalence data. Then, focusing on anxiety disorders, I used random effects meta-regression to explore sources of variability (methodological and substantive) in the prevalence data. Next, a global prevalence model of anxiety disorders was derived using a Bayesian meta-regression tool (DisMod-MR). The model input included data sourced iii through the systematic review and expert input. The data were adjusted for methodological differences identified in the preliminary meta-regression and then estimates derived for populations where data were lacking based on epidemiologically similar populations and country-level covariates such as exposure to conflict. Years of life lived with disability (YLDs) were calculated based on prevalent cases multiplied by an average disability weight taken from the weights allocated to severity proportions (mild, moderate and severe). YLDs and disability-adjusted life years (DALYs) were calculated by sex and age across 21 world regions for 1990, 2005 and 2010. The proportion of burden attributable to anxiety disorders was compared with other mental and physical disorders to provide an objective evidence base to inform decision making in global health policy and service provision. Findings Anxiety disorders were common, with an average point prevalence of 4.0% (95%UI 3.8– 4.3%) and were associated with a high degree of health loss due to the disability resulting from these disorders. In 2010, they accounted for 390 YLDs/DALYs per 100,000 persons (95%UI 191–371/100,000), making anxiety disorders the sixth leading cause of global disability, in terms of YLDs. While there was no direct mortality associated with anxiety disorders in GBD 2010 7% of suicide deaths were attributed to anxiety disorders. Between 1990 and 2010, crude YLDs from anxiety disorders increased by 36%. There was no detectable change in the prevalence of anxiety disorders over the past two decades. The increase in absolute YLDs was explained by global population growth and population ageing. Females accounted for 65% of the DALYs caused by anxiety disorders. The age pattern was similar for both sexes, with YLD rates peaking in the 15–34-year age group: 387 YLDs per 100,000 males and 721 YLDs per 100,000 females. Higher YLD rates were found in high-income GBD regions (North America High Income, Australasia, and Southern Latin America) and in regions with populations exposed to conflict (North Africa/Middle East and Central Europe), while lower rates were found in East Asia. There was considerable uncertainty around estimates, particularly for regions where no empirical data were available. Implications Anxiety disorders are chronic, disabling conditions, and the findings reported here show for the first time their public health significance. To respond to the high burden and low treatment rates of anxiety disorders, policy makers and clinicians in all countries need to ensure cost-effective interventions are widely available. Estimates of prevalence and disease burden could be improved by strengthening the quality of epidemiological data, and identifying whether variations in regional distributions of anxiety disorders are substantive or an artefact of cultural or methodological differences.

The global burden of anxiety disorders: challenges in calculating prevalence and burden of disease using anxiety disorders as a case-study

Acute Care Visits for Eating Disorders Among Children and Adolescents After the Onset of the COVID-19 Pandemic.

Background Individuals with eating disorders have a high mortality risk. Few population-based studies have estimated this risk in eating disorders other than anorexia nervosa. Aims
 To investigate all-cause mortality in a population-based cohort of individuals who received hospital-based care for an eating disorder (anorexia nervosa, bulimia nervosa or eating disorder not otherwise specified) in Ontario, Canada. Method
 We conducted a retrospective cohort study of 19 041 individuals with an eating disorder from 1 January 1990 to 31 December 2013 using administrative healthcare data. The outcome of interest was death. Excess mortality was assessed using standardised mortality ratios (SMRs) and potential years of life lost (PYLL). Cox proportional hazards regression models were used to examine sociodemographic and medical comorbidities associated with greater mortality risk. Results
 The cohort had 17 108 females (89.9%) and 1933 males (10.1%). The all-cause mortality for the entire cohort was five times higher than expected compared with the Ontario population (SMR = 5.06; 95% CI 4.82–5.30). SMRs were higher for males (SMR = 7.24; 95% CI 6.58–7.96) relative to females (SMR = 4.59; 95% CI 4.34–4.85) overall, and in all age groups in the cohort. For both genders, the cohort PYLL was more than six times higher than the expected PYLL in the Ontario population. Conclusions
 Patients with eating disorders diagnosed in hospital settings experience five to seven times higher mortality rates compared with the overall population. There is an urgent need to understand the mortality risk factors to improve health outcomes among individuals with eating disorders.

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Excess mortality associated with eating disorders: population-based cohort study

OBJECTIVE To determine the risk of diabetic ketoacidosis (DKA) and all-cause mortality among adolescents and young adults with type 1 diabetes with and without an eating disorder. RESEARCH DESIGN AND METHODS With use of population-level health care administrative data covering the entire population of Ontario, Canada, all people with type 1 diabetes aged 10–39 years as of January 2014 were identified. Individuals with a history of eating disorders were age- and sex-matched 10:1 with individuals without eating disorders. All individuals were followed for 6 years for hospitalization/emergency department visits for DKA and for all-cause mortality. RESULTS We studied 168 people with eating disorders and 1,680 age- and sex-matched people without eating disorders. Among adolescents and young adults with type 1 diabetes, 168 (0.8%) had a history of eating disorders. The crude incidence of DKA was 112.5 per 1,000 patient-years in people with eating disorders vs. 30.8 in people without eating disorders. After adjustment for baseline differences, the subdistribution hazard ratio for comparison of people with and without eating disorders was 3.30 (95% CI 2.58–4.23; P CONCLUSIONS Adolescents and young adults with type 1 diabetes and eating disorders have more than triple the risk of DKA and nearly sixfold increased risk of death compared with their peers without eating disorders.

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Diabetic Ketoacidosis and Mortality in People With Type 1 Diabetes and Eating Disorders.

Key Points Question Are electrolyte abnormalities in outpatient lab work associated with an eating disorder diagnosis in the future? Findings In this population-based case-control study of individuals with and without an incident eating disorder, an outpatient electrolyte abnormality 3 years to 30 days prior to diagnosis was associated with 2.1-fold higher odds for the subsequent diagnosis of an eating disorder, a significant difference. Meaning These results suggest that otherwise unexplained outpatient electrolyte abnormalities may serve to identify individuals who should be screened for an underlying eating disorder.

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Analysis of Electrolyte Abnormalities in Adolescents and Adults and Subsequent Diagnosis of an Eating Disorder

Objective:Eating disorders are common and have a high public health burden. However, existing clinically relevant data sources are scarce, limiting the capacity to accurately measure the burden of ...

Identifying Individuals with Eating Disorders Using Health Administrative Data.

Chronic psychotic disorders are severe and disabling mental disorders associated with poor psychiatric and medical outcomes, and among the most costly mental disorders to treat. Understanding trends in aggregate health care expenditures over time, and respective drivers, can provide relevant insights for decision makers, namely around appropriate allocation of scarce resources within the health care sector. Using administrative health care times series data from Ontario, this analysis examined trends in aggregate public health care expenditures and activity from 2012 to 2019 among all individuals with a diagnosis of a chronic psychotic disorder. Total aggregate health care expenditures for individuals with a chronic psychotic disorder in Ontario increased at a moderate rate over this time period, in line with the growth of the number of people diagnosed, and thus not likely driven by unit costs or resource use. Psychiatric hospitalizations made up the largest share of health care expenditures (~30%). Nonetheless, among all health services, expenditures of acute medical hospitalizations, outpatient prescription drugs and home care saw the largest growth over time. Mean/per capita health care expenditures were greater for females, and increased with age as well as with the presence of comorbidities/chronic conditions. In particular, mean/per capita health care expenditures increased steadily with the number of comorbidities and were highest for individuals with 5 or more comorbidities and those with congestive heart failure, highlighting the ever-increasing importance of addressing physical health conditions among this patient population. These findings will have important implications for decision makers, namely around the appropriate allocation of health care resources for patients with chronic psychotic disorders. Future research should continue to monitor health care expenditures for individuals with chronic psychotic disorders as well as extend this analysis beyond 2019 to understand how the COVID-19 pandemic, and resulting lockdowns, has impacted aggregate health care expenditures and outcomes for patients living with chronic psychotic disorders.

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Health Care Expenditures Among Individuals With Chronic Psychotic Disorders in Ontario: An Analysis Over Time

This cohort study examines the characteristics and costs of children and adolescents in Canada with high health care costs who use mostly mental health care, the proportion of patients with persistently highest costs, and the factors associated with persisting in a high-cost state.

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Mental Health Care Use Among Children and Adolescents With High Health Care Costs in Ontario, Canada

INTRODUCTION
Mental health care is often managed in primary care with limited specialist support, particularly in rural and remote communities. Continuing professional development programs (CPD) can offer a potential solution to further mental health training; however, engaging primary care organizations (PCOs) can be challenging. The use of "big data" to identify factors influencing engagement in CPD programs has not been well studied. Therefore, the aim of this project was to use administrative health data from Ontario, Canada to identify characteristics of PCOs associated with early engagement in a virtual CPD program, Project Extension for Community Healthcare Outcomes (ECHO) Ontario Mental Health (ECHO ONMH).


METHODS
Ontario health administrative data for fiscal year 2014 was used to compare the characteristics of ECHO ONMH-adopting PCOs, and their patients, to nonadopter organizations (N = 280 vs. N = 273 physicians).


RESULTS
ECHO-adopting PCOs did not differ with respect to physician age or years of practice, although PCOs with more female physicians were somewhat more likely to participate. ECHO ONMH adoption was more likely in regions with lower psychiatrist supply, among PCOs using partial salary payment models, and those with a greater interprofessional complement. Patients of ECHO-adopters did not differ on the basis of gender or health care utilization (physical or mental health); however, ECHO-adopting PCOs tended to have patients with less psychiatric comorbidity.


CONCLUSION
Models such as Project ECHO, which deliver CPD to primary care, are advanced to address lack of access to specialist health care. These findings support the use of administrative health data to assess the implementation, spread, and impact of CPD.

Using "Big Data" to Provide Insights into Early Adopters of Continuing Professional Development: An Example from Project ECHO.

OBJECTIVES
To determine if and to what degree neighbourhood-level marginalization mediates mental health service use among transgender individuals.


METHODS
This retrospective cohort study identified 2,085 transgender individuals through data obtained from 4 outpatient community and hospital clinics in 3 large cities in Ontario, which were linked with administrative health data between January 2015 and December 2019. An age-matched 1:5 comparison cohort was created from the general population of Ontario. Outcome measures were analysed from March 2020 to May 2022. The primary outcome was mental health service utilization, which included mental health-related visits to primary care providers, psychiatrists, mental health- and self-harm-related emergency department visits, and mental health hospitalizations. Mediation variables included ethnic concentration, residential instability, dependency, and material deprivation at the neighbourhood level and were derived from the Ontario Marginalization Index.


RESULTS
This study identified 2,085 transgender individuals from participating outpatient community and hospital clinics, who were matched to the general population (n = 10,425). Overall, neighbourhood-level marginalization did not clinically mediate mental health service use. However, transgender individuals were more likely to be exposed to all forms of neighbourhood-level marginalization, as well as having higher rates of health service use across all outcome measures.


CONCLUSIONS
In this study, mental health service use among transgender individuals was not clinically mediated by marginalization at the neighbourhood level. This study highlights the need to explore marginalization and mental health service use at the individual level to better understand the mental health disparities experienced by transgender individuals and to ensure that health-care services are inclusive and affirming.

Tomi Iwajomo

Papers

Identifying Individuals with Eating Disorders Using Health Administrative Data.

Health Care Expenditures Among Individuals With Chronic Psychotic Disorders in Ontario: An Analysis Over Time

Mental Health Care Use Among Children and Adolescents With High Health Care Costs in Ontario, Canada

Using "Big Data" to Provide Insights into Early Adopters of Continuing Professional Development: An Example from Project ECHO.

Exploring Mediators of Mental Health Service Use Among Transgender Individuals in Ontario, Canada.